<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
			var a = prompt("请输入需要几行")
			for(var c = 0 ; c <= a ; c++){
				for(var i = 0 ; i < c ; i++){
				document.write("*");
				}
				document.write("<br />");
			}
		</script>
	</head>
	<body>
	</body>
</html>
